These days, various allergic diseases such as atopic dermatitis, bronchial asthma and allergic rhinitis have become a problem. Such allergic diseases is mainly caused by an increase in the amounts of allergens in the living space, such as allergens of Acari in houses, especially those of Dermatophagoides (Der 1, Der 2) abundantly existing in house dust and allergens of Cryptomeria japonica pollens (Cry j1, Cry j2) abundantly floating in the air mainly in the spring.
Here, Dermatophagoides itself does not serve as allergens but the dead bodies and excrement of Dermatophagoides serve as allergens. Thus, eradication of Dermatophagoides with an acaricide does not a fundamental solution for allergic diseases. On the contrary, the eradication of Dermatophagoides causes an increase in the number of the dead bodies, and thus may worsen allergic conditions.
The allergens of Cryptomeria japonica pollens Cry j1 and Cry j2 are a glycoprotein with a molecular weight of about 40 kDa and a glycoprotein with a molecular weight of about 37 kDa, respectively. The allergens of Cryptomeria japonica which is attached to the nasal mucosa and the like mucosae are recognized as foreign matter and cause inflammatory reactions.
In order to mitigate allergic symptoms or prevent new allergic symptoms, it is required to perfectly remove allergens from the living space or inactivate allergens by treatments such as denaturalization thereof.
Since allergens are proteins, allergens denaturalized by heat, strong acids, strong bases or other factors presumably lose their allergenic activities. Allergens have very high stability, however, and are not easily denaturalized by factors safely usable at home such as oxidants, reducing agents, heat, alkalis and acids (see Non-Patent Document 1).
In addition, the attempt to denaturalize the allergens contaminating target articles may cause damages on the target articles contaminated by the allergens according to the conditions. Examples of the target articles include tatami mats, carpets, floors, furniture (e.g. sofas, upholstered chairs and tables), bedclothes (e.g. beds, futons and sheets), articles used inside vehicles (e.g. seats and child restraint systems), interior materials for vehicles (e.g. ceiling materials), kitchen utensils, baby goods, curtains, wall papers, towels, clothes, stuffed toys, other textile products and air cleaners (including the bodies and the filters thereof).
Thus, there have been devised methods for chemically denaturalize the surfaces of allergen molecules under relatively mild conditions. For example, there are proposed a method for inhibiting allergens with tannic acid that is used for tanning rawhides (Patent Document 1); a method for inhibiting allergens with tea extracts or the like substances (Patent Document 2); and a method for inhibiting allergens with hydroxy benzoic acid-type compounds or salts thereof (Patent Document 3). Allergen-inhibiting effects are confirmed in these methods.
Here, most compounds used in these methods are a type of polyphenols, and each has a color. Thus, these compounds disadvantageously color the target articles.
Patent Document 4 proposes a method for inhibiting allergens with aromatic hydroxy compounds, which provides improvement in the problem of coloring the target articles. In the case of treating a target article having a light color such as white, however, coloring may occur and the improvement effects are insufficient.    Non-Patent Document 1: The journal of Immunology Vol. 144, 1353-1360    Patent Document 1: Japanese Kokai Publication S61-44821 (JP-A S61-44821)    Patent Document 2: Japanese Kokai Publication H06-279273 (JP-A H06-279273)    Patent Document 3: Japanese Kokai Publication H11-292714 (JP-A H11-292714)    Patent Document 4: Japanese Kokai Publication 2003-81727 (JP-A 2003-81727)